The vascular system of the human is subject to blockage due to plaque within the arteries. Partial and even complete blockage of arteries by the formation of an atherosclerotic plaque is a well-known and frequent medical problem. Frequently, such blockage occurs in the coronary arteries. Blockages may also occur secondary to past treatment of specific sites (restenosis—such as that stemming from rapidly dividing smooth muscle cells). In addition, blockages can also occur in the context of peripheral arteries.
Blockages may be treated using atherectomy devices, which mechanically remove the plaque; hot or cold lasers, which vaporize the plaque; stents, which hold the artery open; and other devices and procedures designed to increase blood flow through the artery.
One common procedure for the treatment of blocked arteries is percutaneous transluminal coronary angioplasty (PTCA), also referred to as balloon angioplasty. In this procedure, a catheter having an inflatable balloon at its distal end is introduced into the coronary artery, the deflated, folded balloon is positioned at the stenotic site, and then the balloon is inflated. Inflation of the balloon disrupts and flattens the plaque against the arterial wall, and stretches the arterial wall, resulting in enlargement of the intraluminal passageway and increased blood flow. After such expansion, the balloon is deflated, and the balloon catheter removed. A similar procedure, called percutaneous transluminal angioplasty (PTA), is used in arteries other than coronary arteries in the vascular system. In other related procedures, a small mesh tube, referred to as a stent is implanted at the stenotic site to help maintain patency of the coronary artery. In rotoblation procedures, also called percutaneous transluminal rotational atherectomy (PCRA), a small, diamond-tipped, drill-like device is inserted into the affected artery by a catheterization procedure to remove fatty deposits or plaque. In a cutting balloon procedure, a balloon catheter with small blades is inflated to position the blades, score the plaque and compress the fatty matter into the artery wall. During one or more of these procedures, it may be desirable to deliver a therapeutic agent or drug to the area where the treatment is occurring to prevent restenosis, repair vessel dissections or small aneurysms or provide other desired therapy.
Additionally, it may be desirable to transfer therapeutic agents to other locations in a mammal, such as the skin, neurovasculature, nasal, oral, the lungs, the mucosa, sinus, the GI tract or the renal peripheral vasculature.